They're not prone to self reflection. They're very used to being told what assholes they are, and just convince themselves that others just don't get it, regardless of evidence to the contrary. Of the ones I've known, they can have their behavior explode in their face, and they'll still compartmentalize it into parts to so they can blame most of it on others, but take fake blame for tiny parts only where it can make them seem sympathetic.
Like, the part with not caring how her book would hurt others is actually EXACTLY something one of them would do. I've talked to the brick wall of "But how does that ACTUALLY affect you?" many, many times. Where when something they do, or want to do, really upsets someone, they're unwilling or unable to empathize with feelings, no matter how you try to explain it, it won't land if you don't frame it in a way where it will negatively impact them. They simply don't feel like they need to justify themselves. That they want to do it is in itself justification enough, though this obviously is a one way street to them.
The problem with the book scene isn't that it's not something a sociopath would do, it's that it's not a behavior (specifically, simply discounting their victim's feelings instead of trying to bribe, placate or justify), one would do without some way to keep those people close. Be it leverage, blackmail, misplaced affection, financial benefits.
As in, she wants to at least keep Futaba and Akira in her life. Likely for self serving reasons, but she does. She wouldn't do things to make them out and out angry with her without some kind of leverage to keep them around. But she literally just showed all her cards and scuttled her leverage. Blackmail? She just published it in a book. Affection? Akira really has none for her, and it's such a betrayal in Futaba's eyes that she risks total cutoff, despite the old friendship.
For a sociopath to do that to someone with no leverage and then act with dismissiveness would mean they no longer see you as a valid asset. They no longer care if you stick around.
But she kinda does in game, it's just everyone simply keeps letting her get away with it.
